Electron deficient metalloporphyrins 1 (e.g. R=C.sub.6 F.sub.5, X=F,Cl,Br,M=Fe) have been shown to be efficient catalysts for the highly selective air oxidation of light alkanes to alcohols (Ellis and Lyons, Cat. Lett., 3, 389, 1989; Lyons and Ellis, Cat. Let 8, 45, 1991; U.S. Pat. Nos. 4,900,871; 4,970,348), as well as for efficient decomposition of alkyl hydroperoxides (Lyons and Ellis, J. Catalysis, 141, 311, 1993; Lyons and Ellis, U.S. Pat. No. 5,120,886).
They are prepared by co-condensation of pyrrole with the appropriate aldehyde (Badger, Jones and Leslett, "Porphyrins VII. The Synthesis of Porphyrins By the Rothemund Reaction", Aust.J.Chem., 17, 1028-35, 1964; Lindsey and Wagner, "Investigation of the Synthesis of Ortho-Substituted Tetraphenylporphyrins", J. Org. Chem., 54,828, 1989; U.S. Pat. Nos. 4,970,348; 5,120,882) followed by metal insertion (Adler, Longo, Kampas and Kim, "On the preparation of metalloporphyrins", J. Inorg.Nucl.Chem., 32, 2443, 1970) and .beta.-halogenation; (U.S. Pat. Nos. 4,8.92,941; 4,970,348). Ellis and Lyons U.S Pat. No. 4,970,348 discloses chromium complexes of meso-tetrakis(trifluoromethyl)beta-haloporphyrins, made by reacting pyrrole with trifluoroacetaldehyde, and halogenating the resulting porphyrin; also, azide and hydroxide complexes of the porphyrins. Ellis and Lyons U.S. Pat. No. 5,120,882 discloses iron and other metal complexes of meso-tetrakis(trifluoromethyl)-beta-nitroporphyrins, obtained by nitration of meso-tetrakis(trifluoromethyl)porphyrin. ##STR1##
Dipyrromethanes (2; see J. D. Paine in "The Porphyrins" D. Dolphin, Ed., Academic Press, New York, Vol. I, pages 101 and 163-234, 1978) are the most commonly used precursors to a wide variety of symmetrical and unsymmetrical porphyrins. The use of dipyrromethanes for the synthesis of porphyrins carrying electron-withdrawing groups in all peripheral positions has been limited by the inaccessibility of 5,5'-unsubstituted dipyrromethanes in which the groups (2; R.sup.2,R.sup.3,R.sup.5,R.sup.6) that become the beta positions, and the group (2;R.sup.4) that becomes the meso positions, of the resulting porphyrins, either electron-withdrawing or hydrogen for appropriate post-cyclization functionalized. ##STR2##
Acid-catalyzed co-condensation of 5,5-unsubstituted dipyrromethanes 3 with aldehydes 4 has been shown to give porphyrins (5; M=2H) in high yield. However, since the precursor dipyrromethanes 3 used in these disclosures are beta alkyl meso-unsubstituted systems (R.sup.1 =R.sup.2 =R.sup.4 =R.sup.5 =alkyl;R.sup.3 =H) and the aldehydes are aromatic aldehydes (R.sup.6 =aryl), the resulting porphyrins 5 are 5,15-diaryl-10,20 unsubstituted porphyrins with alkyl substitution at the beta positions (R.sup.1 =R.sup.2 =R.sup.4 =R.sup.5 =alkyl) (Ogoshi, Sugimoto, Nishiguchi, Watanabe, Matsuda and Yoshida, "Syntheses of 5-Aryl and 5,15-diaryl-2,3,7,8,12,13,17,18 Octaethylporphines" Chemistry Lett., p.29, 1978; Gunter and Mander, "Synthesis and Atropisomer Separation of Porphyrins Containing Functionalized at the 5,15-Meso Positions: Application to the Synthesis of Binuclear Ligand Systems", J. Org. Chem., 46, 4792, 1981; Young and Chang, "Synthesis and Characterization of Blocked and Ligand-Appended Hemes Derived from Atropisomeric meso Diphenylporphyrins", J. Am. Chem.Soc." 107, 898, 1985; Osuka, Nagata, Kobayashi and Maruyama, "An Improved Synthesis of 5,15-Diaryloctaalkylporphyrins`, J. Heterocyclic Chem., 27, 1657, 1990).
The fully unsubstituted dipyrromethane 3 (R.sup.1 =R.sup.2 =R.sup.3 =R.sup.4 =R.sup.5 =H) has also been condensed with substituted aromatic aldehydes 4 to give beta-unsubstituted 5,15-diarylporphyrins which are also unsubstituted at the other two meso positions 10 and 20 (5 R.sup.1 =R.sup.2 =R.sup.3 =R.sup.4 =R.sup.5 =H; R.sup.6 =aryl); Manka and Lawrence, "High Yield Synthesis of 5,15-Diarylporphyrins", Tetrahedron Lett., 30, 6989, 1989). ##STR3##
M. Homma et al, Tetrahedron Lett. 24, 4343 (1983) disclose Cu, Zn and Co complexes of porphyrins containing trifluoromethyl groups in .beta. (beta) positions, such as 1,3,5,7-tetrakis(trifluoromethyl)-2,4,6,8-tetraethylporphyrin.
N. Ono et al, Bull.Chem.So.Jpn. 62, 3368 (1989) also disclose zinc complexes of porphyrins containing trifluoromethyl groups in .beta. positions, for example 1,3,5,7-tetrakis(trifluoromethyl)-2,4,6,8-tetramethylporphyrin.
Hoffman, Robert and Meunier, "Preparation and catalytic activities of the manganese and iron derivatives of Br.sub.8 TMP and Cl.sub.12 TMP, two robust porphyrin ligands obtained by halogenation of tetramesitylporphyrin`, Bull.Soc.Chim.Fr., 129, 85, 1992, disclose ionic halogenation of tetramesitylporphyrin by N-bromosuccinimide or N-chlorosuccinimide to give as main product, meso-tetramesityl .beta.-octabromoporphyrin and meso-tetrakis(3-chloro-2,4,6-trimethylphenyl-.beta.-octachloroporphyrin, respectively, and that manganese and iron derivatives of these porphyrins are efficient catalysts for olefin epoxidation and alkane hydroxylation.
Lyons and Ellis, "Selective Low Temperature Hydroxylation of Butane By Molecular Oxygen Catalyzed By an Iron Perhaloporphyrin Complex", Catalysis Lett., 8, 45, 1991 disclose synthesis of iron tetrakis(pentafluorophenyl).beta.-octabromoporphyrinato complexes, having unprecedented catalytic activity for the reaction of molecular oxygen with isobutane to give tert-butyl alcohol.
Bhyrappa and Krishnan, "Octabromotetraphenylporphyrin and Its Metal Derivatives: Electronic Structure and Electrochemical Properties", Inorg.Chem., 30, 239, 1991 disclose V.sup.IV O, Co(II), Ni(II), Cu(II), Zn(II), Pd(II), Ag(II) and Pt(II) derivatives of octabromotetraphenylporphyrin, and their electronic structure and electrochemical properties.
Onaka, Shinoda, Izumi and Nolen, "Porphyrin Synthesis in Clay Nanospaces", Chemistry Lett., 117, 1993 disclose synthesis of meso-tetraalkylporphyrins from aliphatic aldehydes and pyrroles by using the clay, montmorillonite.
Gong and Dolphin, "Nitrooctaethylporphyrins: synthesis, optical and redox properties", Can.,J.Chem, vol. 63, 1985, pages 401-5, disclose reaction of zinc octaethylporphyrin with N.sub.2 O.sub.4 in dichloromethane to give, in a step-wise reaction, the zinc complexes of mono-, di-, tri- and tetra-nitrooctaethylporphyrins, and demetallation of the products under acidic conditions to give the corresponding free base. The meso-nitro groups exert steric and electronic effects on the porphyrin macrocycle. N-protonation of the nitrated species causes a distortion of the ring and gives an optical spectrum similar to that of protonated meso-aryl substituted porphyrins. The nitro groups make the oxidation of the porphyrin ring more difficult and facilitate the ring reductions.